Locating grounds on electric circuits.



Patented luly 23, |901. v

E. M. HEWLETT.

LUCATING GRGURDS- EN ELECTRIC CIRCUITS.

.(Appxininn med Mar. 14, woo.;

.No Model.;

il* QQ@ E Q m l N I E@ K r I 2 T-hl* L E 4f\ t 2 Wtnesses: fr Jrwentor Om .-J Edward M Hewleht r 74,6 g WWJM. Aug,

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` f EDWRDEM. nnivnnfruvo-n-'scnnnnernnrgl f GENERAL.' ELECTRC QQMPANY@ @KNEW X031?- `LocA "iiue neon Meson eteornie:cinoulrs l NWYORK;

SEEIFICATIoNforming part of Letters Patent-No. 618,878, dated July 23,' 1901. i Appiitautnsummum,1900i seriousness. (nommen i 1 To tZZ'zotont'it'tcoy concern:

Be it known that I, EDWARD M; HEWLETT,

j a citizen of the United States, residing at ,Schenectadygiujthe county of Schenectady 5 and' State of Neuy York, have invented certain new 'anld useful Improvements in Locating Groundson Electric Circuits, (Case No.

' 854,)of ivhichthe following is a specification.

In operating electrical distribution systerns IQ considerable difculty is experienced in loveating gro un'ds when they occur in the system, and much valuable time is'spent and great annoyance is caused by the failure toknow quickly just where the ground has occurred;

I5 It is the object of my invention to permit the ground to be located from the distributingstation, soit-hat lineman may be sent diiectlyto Athe spot Where the damage exists 'and the line quickly putinto serviceable con` 2o diti'o'ni Y In vcarrying out my invention I provide at the dis'trib'utirig-station a source of 'high'electric potential, by which an arc maybe formed atthe point at which the ground occurs by 25 connecting the high-potential source with the distributing system; Connected to the two distributing-mains is a dilerential indicator,`

which may be adjusted to a zero position by1 means `of variable resistances or other del 3e vicesyso that ina normal. condition of the' line, supposing no leakage exists at any point,

the vinstrument ighen connected with the testing source Would'stand at a determinate po. sition; but if a leak exists on either line the.-v

3 5 -two forces operating the instrument would be unbalanced and a deflection given. iViren the instrument shows a deflection, the rsistances orother compensating devicesinay be adjust! ed until it is again brought to zero or the 4o point at which it would stand if the line were not grounded, and the amount of resistance.

so added affords a factor from which the point at which the ground occurs may be easiiy determined. i provide also a switch at the dis- 4'5 tributing-station by which the grounded main may be connected to a return-Wire, so that the resistance of the loop being tested may be easily ascertained. The preferable arrange nient is to so place the switch that the two 5o inains may be connected in series relation. NVith this organization the two sides of the definitely indicated in the claims, appended l differential instrument are included in a loop,

one end of which is grounded at the station through vthe arc-machine or other source of high potential andthe otherend of whiclris '55 a possible groundat some point out on the system. This Vloop is normally open; but

cach substation is provided with means for closingit,so that an attendant may insert a 'plug-and' complete the testing-circuit when 6o advised by telephonel to do so.

' Myinvention therefore comprises a distrib-y uting system providedat some point with an instrument vand means for determining the resistance of each side of the circuit' to any 65 point within the 'range of the'system.

It comprises other features, ,the novelty of. which 'will he hereinafter described, and

hereto. Y 7o In the accompanying-drawing, irhich is a diagram illustrating myimprovements, l represents a distributing-station, ativhich are located the supply-generators and the'testing apparatus. j

2 and 3 represent feeders leading from the distributing station to fout-lyingv points. Where there are subst-ations,- I provide means at eac-l1y substation, `sueh'as a plug-switch, (indicated'at 4,) bywhich a'cross'c'onnection 8o maybe made between the di'stributingnrains.

Where no such distributinstationl is4 employed, an auxiliary feeder insulated from the main feeder, but connected at itsouter end, may beemp'loyed.' VAt the generating V85'. st'etiou'l provide a source of high'poteutialv as, for example, an arc-machine 5, ,including an amperefm'eter in series relation` and a -voltmeter 7 inshunt relation to its leads, one

end-of thein'achine being grou nded'at tliersta- 9o tion through a switch S and the other end be ing connected with a point), common to the two coils, of a dilerential indicator 10 10, the index of which is provided Withan armature l1, mounted in the common field of the 95 coils. i

. The instrument may be variously organized, and the type shown in the drawing is' merely illustrative. This comprises two in elined coils 10 10, which when equally ener- .ma gized support the needle at its zero position; but when one predominates over the other sos theaimatnre tends to' set itself more nearly infalineinent'jwith ,the predominating coil therebytilting vthe index toward said coil.

' -The free terminals of lthese two. coils connect with variable resistances 1212, the ends of which connect withthe distribution-leads 2 represents generating outfit of the station, which maybe of any approved or desired type'. In the return-lead'for the testinggenerator is' a switch 14, which may, be shifted from thecontact which puts the coil 10 in circuit to a normally open contact-15, by which the distributng-mains'are put-in series relation tothe4 high-potential' machine 5, and whenso'shiftedthe resistance of the distrib'- utng-mains may be easily-determined.

p Vhen' the system is in normal operation,l l no ground exists.,VA If Athe switches are closed,

ccthe coils v1 0 10a will'fbe equally energized and the indicator wil'lstand at zero; In case of a ground -however, the'needlewill tilt toward 1hab sidepf bhp instrument containing the coil corresponding t'oqthe'side grounded. 25.

In 'such case the switch Iltis in` the position indicated in the d iagratnand theground-switch 8" is closed and the arcgenerator started.

Thi s"geuerates sufficient potential` to spring i #1an arc at thepoint `where, the ground. occurs, thereby masinsjagreuusled.- circuit, for the.

, arc-machine,'oneigronndexistingf atthe st a`. tien .and the other atthedamagedfpont on the line. Before connectingup the arc-machine i the central-station attendant will havel telef` phoned to a substatiominstructin g the attend,-

aprnQcompletetbe cross connectOll al? the plug-switch 4. 'i

r inclding-thetvvoQilslO l0,oneside of which fis .Qt-less resistacethau the btlie1'-nemly,' that onwhichthe ground occurs. Either o'r -the meins dition-tithe, distance may be 0.0mlllllflzifP-Qm' kllfvndata, ais-.tn th'eirfcharacter.

f'-nQ'fQSSentiallouali systems'that a, high- .m9115181 Sbllrellbeused: un.. thetestingcir-w v- 4both. of the-resistancesj12` 12 are Itheriadjf he grouudinrarid the.' 'Swie- OPOSSs-.Se-ctien, .from which 'bly 'au lellfletmi the Y. distance. may betieten. mined nd'tlxfe'g'round instantly located. .Iii

cuit, as the dierential instrument may be s niciently refined 'to respond to a ground.-

under a low-potential source.

What I claim as new, and desire tolsecure by Letters'Patent of the United States, is-

1. In a 'system of electrical distribution,

one pole grounded, connectionsin parallel' between the other pole and the sides ofthe circuit, and means for determining the relative resistance'of the two branches of the system to. the pint at'which a ground may exist.` 2. In a system of multiple-arc electrical distribution, means for completing a cross connection of the distributing-mains ata point distant from the distributing-station,

and means for determining the ,relative're-f sist'anceof the two branches ofthe distribution-circuit from' the distributing-station toa point'at whichthe leakage may occur. l. 3. KInasystemoiv electrical distribution, a grounded source of highpotentialat the dispar-allel relation to the 'distributing-mains,-

land means for determini-ng the resistance ot' ,each branch circuit thus produced to any fp ointin the. system, at which a ground may occur,

4,. In a; systemiof electricalI distribution, a

'dijerential'instrument located at av deter- /minate point of the system, the two sides of .which connect with the distributing-mains,

means for'imposing potential in parallel on said mains, and means for determining the r relative resistance .of the two branches to any 5. Ina system of electrical distribution, a.4

high-potential generator, located at a. determinate point, one end of which is grounded, a. d ijerential instrument having its tWo. controlling-cousin parallel relation to lthe, other 'terminalof the generator, al variable resist-- ance, in series with each coil, and connections,

betweentlie resistances andthe distributingmains. l

In 'wit ness whereof Ihave hereunto set my handtliis, 10th day 0f .'Mluh, 1900.

EDWARD M'. HEWLETT.

Witnesses: i

u BENJAMIN B. HULL,

MABEL E; JAGOBSON.

ftributing-station, means for grounding eine' jpole, :means for connectingthe other polefin IOO 6o' means for locating the position in the circuit'.l

of a ground comprising a generator having 

